Washington, USA: World number two Caroline Wozniacki, the reigning Australian Open champion, withdrew from the WTA Washington Open on Tuesday with a right leg injury, the tournament announced.
The 28-year-old Dane won her 29th career WTA title in June at Eastbourne but was ousted from Wimbledon in the second round.
Top seed Wozniacki said after practice Monday she had a right leg issue.
"It's just something that has been nagging for a little while," Wozniacki said. "Hopefully it will be fine."
Wozniacki captured her first Grand Slam title at Melbourne in January, returning to world number one after a six-year gap, the longest span between reigns in women's tennis history.
Wozniacki withdrew hours before her scheduled opening match against Ukraine qualifier Anhelina Kalinina. She will be replaced in the draw by qualifying lucky loser Ysaline Bonaventure of Belgium.
With Wozniacki out, the top-ranked player in the tournament is world number three Sloane Stephens, the reigning US Open champion.